Natural history of long-COVID in a nationwide, population cohort study

Previous studies on the natural history of long-COVID have been few and selective. Without comparison groups, disease progression cannot be differentiated from symptoms originating from other causes. The Long-COVID in Scotland Study (Long-CISS) is a Scotland-wide, general population cohort of adults who had laboratory-confirmed SARS-CoV-2 infection matched to PCR-negative adults. Serial, self-completed, online questionnaires collected information on pre-existing health conditions and current health six, 12 and 18 months after index test. Of those with previous symptomatic infection, 35% reported persistent incomplete/no recovery, 12% improvement and 12% deterioration. At six and 12 months, one or more symptom was reported by 71.5% and 70.7% respectively of those previously infected, compared with 53.5% and 56.5% of those never infected. Altered taste, smell and confusion improved over time compared to the never infected group and adjusted for confounders. Conversely, late onset dry and productive cough, and hearing problems were more likely following SARS-CoV-2 infection.

Automated summary

Previous studies on long-COVID have been limited, and without comparison groups, it is difficult to differentiate disease progression from symptoms caused by other factors. The Long-COVID in Scotland Study (Long-CISS) conducted a cohort study in Scotland, comparing adults with laboratory-confirmed SARS-CoV-2 infection to PCR-negative adults. The study found that individuals with previous symptomatic infection had a higher prevalence of symptoms compared to those who were never infected, with altered taste, smell, and confusion improving over time, and late onset dry and productive cough, and hearing problems being more likely following SARS-CoV-2 infection.